The proposed research continues a prospective study of maternal growth during adolescent pregnancy and its potential sequelae. It has already been shown that growth during pregnancy, estimated using the Knee Height Measuring Device (KHMD) since serial measurements of stature are insensitive, is associated with larger gestational weight gains, continued accrual of subcutaneous fat, and retained weight postpartum. However, despite the large weight gains, infant size is reduced (-150-200 g) in the presence of maternal growth, and maternal growth is associated with evidence of diminished placental blood flow and reduced levels of micronutrients (e.g., ferritin, folate) in cord blood. The purpose of this study is to determine whether or not the milieu which underlies adolescent growth, i.e., higher levels of fasting insulin and insulin-like growth factor-I (IGF-1), is also present during adolescent pregnancy and underlies maternal growth by KHMD and the observed changes in body composition and mediates the association between maternal growth and reduced infant birth weight through its effect on the substrate supply of pregnancy (e.g., glucose and branch-chain amino acids). Further, since the transient increase in insulin at adolescence may be more likely to become permanent with the weight retention associated with maternal growth, it is hypothesized that adolescent multiparas and mature women with a history of adolescent childbearing will have increased levels of fasting insulin, be characterized by an increased risk of overweight and obesity, a centripetal fat distribution, and continued reductions in birth weight. A prospective cohort study is proposed to address these aims, comparing 600 adolescent primiparas and multiparas (<18 y) and 600 mature women (19-29 y). Of the mature gravidas, half of the multiparas (n=150) will have had a history of adolescent childbearing. Subjects will be followed through pregnancy with measures of fasting insulin, IGF-I, body composition, and the substrate supply of pregnancy, and into the postpartum at 4-6 weeks and 6 months to determine the effects of hyperinsulinemia on weight gain, weight retention, and pregnancy outcome and long-term effects on the persistence of overweight and higher insulin levels in the postpartum period. The investigators state that if the proposed hypotheses are verified, then the results would help to explain some of the ethnic differences in birthweight because of the increased rate of teenage childbearing among minority women and underscore what may be the long- term consequences of adolescent pregnancy, to wit, overweight, obesity, and increased risk for cardiovascular disease and non-insulin dependent diabetes mellitus.